It is of the utmost importance to not lose your shiet and flame like the great fire of 1666 when you are playing support in League of Legends. Why? Because, contrary to what every Ashe ever has told you, the ADC is not the carry. You are. You are a magnificent, selfless hero for choosing to support in a game where every second player is an egotistical prick who considers it their moral and spiritual duty in life to at least get 20 kills in one game (and if they don't, it's your fault. Clearly). It takes a certain kind of person to main support. It's not for the faint of heart. You are the glue that holds your team together, the one who can turn the tide of any team fight with a well-placed stun or a gloriously infuriating grab.
Now that I've patted myself on the back for ten minutes, let's begin.

The first step on the path to gentility as a support is to bring the summoner spell Exhaust with you. You can take Heal if you really really want to, but remember - nothing gets you into the good graces of your ADC than giving them as many kills as possible. This is gentlemanly. It is not proper to kill steal; your job is to set up kills, and get assists, and make sure your ADC doesn't do something stupid. It's a big job, yes, but only you can do it - top is a galaxy away, jungle doesn't actually care about you, and mid has to fend off the obnoxious Yasuo. To set up a kill, wait until your foe is in a vulnerable position and throw a little stun their way, or a little slow, or in the case of Morgana, a completely ludicrous 3-second stun and an evil purple puddle just to make whoever got snared feel even worse about themselves. Now you hit them with Exhaust - or you can wait until you think they might be about to get away. If your ADC is good they'll jump on the chance and ta-dah, first blood.
It's after the kill, not before or during, where you must truly show your gentlemanliness. Immediately throw up a little "gj" in chat. (Yes - I know you were an integral part of that kill, but you can't say that. In a better world you would write "good job jumping on that opportunity that I created for you", but the ADC will not appreciate it. No one will appreciate your hard work - that's your lot in life). If your ADC doesn't reply with the courteous "you too", don't take it to heart. It's when the ADC continues to ignore you completely that you really need to start showing your nobleness as the perfect support. We'll get to that next...

This, my friends, is the big one.
How do you deal with an ADC who is just a complete and utter prick? Many of us would be tempted to bite back at them. TARIC YOU FECKING IDIOT, (they have been known to write), WHY DIDNT U JUMP ON HIM WHEN YOU COULD HAVE, to which I have once upon a time replied, in tones of forced politeness, "Why, Ashe, I didn't jump on him because I was out of mana and at eleven health. Also, so were you. That, I'm afraid, is why I didn't jump on the full health, full mana Kalista."
Unfortunately, sometimes the ADC either can't or won't accept that they're a complete idiot and that you had the better judgment in that situation. But that's all right. We're not here to make our ADCs reasonable people - we're here to keep ourselves gentlemanlike and to hopefully at least keep them from feeding in the first ten minutes of the game.
How do you do that? You don't reply to them. That's how. Or, if you really have to, you mute them. After you're both dead to the now-fed Katarina, and after they begin to have a go at you, merely head nobly back into lane with your mouth firmly shut. Do not engage in an argument with this person; it's likely they're some kind of monkey who has unwisely been gifted with a keyboard by their scientist caretakers.
If, after you've been silent and returned to the game, trying as hard as you can to make up for your losses, the ADC continues to berate you - continue to say nothing. You might consider typing the impersonal and always-helpful "i'm muting you [username of player] so i won't hear you if you're trying to tell me something". That of course is a last resort. Yes it's awful to put up with a toxic ADC, but remember, you ARE the better person. You're the one who's decided to selflessly play the overlooked but integral role of support. You do not seek glory - glory seeks you.

There are endless ways for an ADC to make your life hell. Very often they will blame all of their mistakes on you. A common refrain is WHY DIDN'T YOU HEAL ME!?. Or, WHY DID YOU LEAVE ME TO DIE, DESPITE THE FACT THAT IF YOU'D TURNED AROUND WE WOULD'VE BOTH DIED?!!?!11 Again, there is no arguing with an unreasonable person. If you're a good support, let your playing do the talking as you continue to nobly support them in lane. Or, just go help mid with that ****ing Yasuo. Either way.
As I said, support rarely has any glory, even if they absolutely deserve it. Sometimes a game will go like this:

Clearly, you, the support, had an excellent game. In the chat room afterwards, your ADC immediately writes 'lol ashe needs a buff', followed by 'taric omg only 1 kill'. They'll write this no matter if you had three billion assists. People tend to look at kills first - even the most gentlemanly of gentlemen is often hardwired to look at that stat before the rest - and so who's going to get the glory? The Ashe is. No matter how toxic, how ungrateful, how genuinely unskilled they might be, if they hit 20 kills people are going to either seethe silently with jealously or write 'gg ashe wp' (if they're unusually courteous people, that is). No one in the history of the universe has ever written 'wow taric you got 34 assists that's crazy' in the chat. NO ONE. But that's okay.
Deep breath.
At the end of the day, it'll usually only be you who will appreciate your assists. It's only you (unless your game's being watched by other reasonable people), who's going to look back at the game and think, "Wow, that was a great game. I was always where I needed to be, I kept my teammates from dying at least a dozen times, and I set up a whole bunch of kills for my ADC and for everyone else." Again - this is your lot in life. A support's glory goes unchecked. You might have set up three billion and six kills. The credit will always go to the Ashe.

Always.

(I mean unless the Ashe is nice, but WHEN DOES THAT HAPPEN AM I RIGHT?)

What, in short, is good about being a gentleman/woman/person? To me, it's the satisfaction of knowing no matter how crazy the rest of your team is, no matter how much the Ashe blamed you for their tower diving escapades (TARIC YOU FCKING IDIOT WHY DIDN'T YOU MAKE THE TURRET DISAPPEAR FOR ME WHEN I RAN THROUGH IT), that YOU always kept a level head, that YOU always tried your best. Many of us, I think, have dissolved into fits of rage at the injustice of being blamed for a bad ADC, or being hated on for our pink fuzzy leg warmers, but what do we get out of doing that? There's nothing good in losing your shiet and freaking out on someone - no, not even if they're being totally unreasonable.
The best support is the support who does their job and supports their teammates, with words (gj, nice, gg), with actions (last-second Kayle ult, for instance), with warnings (rengar coming top), with heart and nobility and most of all, with utter gentlemanliness. This is the support everyone should aim to be. And, with enough positivity, maybe Riot will one day accept the thing everybody already knows - Taric loves pink, and that's all right.

Love, Lord Houseplant.